In textile machinery manufacturing, textile machines having a large number of identical workstations have been known for a long time in various embodiments and described in relative detail in numerous patent specifications.
Textile machines of this type, frequently also known, as multiple station textile machines are, for example, rotor spinning machines, texturing machines, flyers, ring spinning machines, two-for-one twisting machines or cabling machines, etc. Multiple station textile machines of this type often have at least one generally continuous drive shaft running in the longitudinal direction of the textile machine, to which yarn processing devices, which are, for example, overhung, are connected.
Two-for-one twisting or cabling machines, for example, have a large number of identically configured workstations of this type, which are arranged next to one another on both sides of the machine longitudinal axis and are, in each case, inter alia equipped with a winding mechanism to produce a cross-wound bobbin. The winding mechanism, in this case, generally has a friction roller for the frictional drive of a cross-wound bobbin and a yarn processing device connected upstream of the friction roller in the yarn course in the form of a so-called overfeed roller, by means of which the yarn tension of the yarn running onto the cross-wound bobbin is adjusted, in other words is generally reduced.
The order of magnitude of the reduction of the yarn tension is determined here by the wrap angle of the yarn around the overfeed roller and by the peripheral speed of the overfeed roller in relation to the winding speed of the cross-wound bobbin. In practice, this means that the cross-wound bobbin driven by the friction roller rotates at a significantly lower peripheral speed than the overfeed roller.
With regard to the drive of the friction rollers and the overfeed rollers, various embodiments are prior art in conjunction with two-for-one twisting machines or cabling machines of this type.
Two-for-one twisting or cabling machines, in which both the friction rollers and the overfeed rollers of a textile machine side are in each case driven by separate drive shafts along the length of the machine, are known, for example, from German Patent Publications DE 34 03 144 A1, DE 42 17 360 C2 or DE 100 45 909 A1. With these known two-for-one twisting or cabling machines, in particular the drive shafts for the overfeed rollers along the length of the machine and located in the working region of the operator have proven not to be very advantageous both from a safety and from an operating point of view. In other words, drive shafts of this type along the length of the machine are generally, as shown in German Patent Publication DE 100 45 909 A1, for example, provided with a casing or a covering to prevent accidents, the casing only being equipped with narrow slots at the workstations. However, with drive shafts of this type along the length of the machine, in the event of an interruption of the yarn travel, for example caused by the tearing of the yarn while being wound onto the bobbin, the problem often occurs that the yarn is picked up by the drive shaft, which continues to rotate, and is wound thereon. The operator then often tends to uncover the drive shaft or the overfeed roller by removing the covering in order to thus improve the accessibility to the wound lap produced.
A procedure of this type is, however, extremely dangerous as the drive shaft continues to revolve with an unreduced speed.
The drawback in drive shafts of this type along the length of the machine is also the poor exchangeability of yarn-transporting components. The changing of an overfeed roller is, for example, relatively complex. It has therefore already been proposed in the past to dispense with drive rollers along the length of the machine, at least for the overfeed rollers, and instead to also drive the overfeed rollers by means of the drive shafts present in any case for the friction rollers.
German Patent Publication DE 10 2005 050 074 A1 describes a two-for-one twisting or cabling machine, in which the overfeed rollers of the numerous workstations are in each case mounted individually on special support elements, which make it possible to pivot the overfeed rollers between an operating position and a service position. The overfeed rollers are also in each case connected by a continuous traction means to one of the two friction shafts along the length of the machine, the continuous traction means, on the one hand, comprising a drive element arranged on one of the friction shafts along the length of the machine and, on the other hand, being drawn onto an output means non-rotatably connected to the overfeed roller. In practice, the arrangement, known per se, of continuous traction means, has proven not to be particularly advantageous, however. In other words, in these two-for-one twisting or cabling machines, an exchange of the continuous traction means “caught” by a friction shaft along the length of the machine and generally configured as a round belt is always, when necessary, relatively difficult and time-consuming, which, as at least one machine side of the two-for-one twisting or cabling machine generally has to be shut down during the change process, has a negative effect on the efficiency of the textile machine.
Two-for-one twisting and cabling machines are also known from German Patent Publication DE 10 2006 061 289 A1, in which the overfeed rollers are in each case connected by a magnetic gearing to a drive shaft, preferably to the friction shaft of one of the two textile machines. Magnetic gearings of this type are relatively insensitive to soiling and have the advantage of great operating reliability.
In contrast to positive torque transmission devices, for example, the exceeding of a limit torque upon the occurrence of an unforeseen operating condition immediately leads to the standstill of the associated overfeed roller in magnetic gearings of this type.
A serious drawback of this magnetic gearing, which is advantageous per se, is, however, its relatively complex construction, which leads to magnetic gearing of this type, in particular in relation to the above-described continuous traction means, being very expensive.